Question

The least magnetic moment will be shown by the transition metal ion with the outer electronic configuration:

• A. $3d^2$
• B. $3d^3$
• C. $3d^7$
• D. $3d^9$

Answer 1

The correct option is D $3d^9$

As magnetic moment is $\sqrt{n(n+2)}$ where n is no. of unpair electron.
$3d^2$ configuration has 2 unpair electron
$3d^3$ configuration has 3 unpair electron
$3d^7$ configuration has 3 unpair electron
$3d^9$ configuration has 1 unpair electron
so lowest magnetic moment will be for $3d^9$ configuration